Molecular Plant Abiotic Stress E-Book
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- Herausgeber: John Wiley & Sons
- Kategorie: Wissenschaft und neue Technologien
- Sprache: Englisch
A close examination of current research on abiotic stresses in various plant species The unpredictable environmental stress conditions associated with climate change are significant challenges to global food security, crop productivity, and agricultural sustainability. Rapid population growth and diminishing resources necessitate the development of crops that can adapt to environmental extremities. Although significant advancements have been made in developing plants through improved crop breeding practices and genetic manipulation, further research is necessary to understand how genes and metabolites for stress tolerance are modulated, and how cross-talk and regulators can be tuned to achieve stress tolerance. Molecular Plant Abiotic Stress: Biology and Biotechnology is an extensive investigation of the various forms of abiotic stresses encountered in plants, and susceptibility or tolerance mechanisms found in different plant species. In-depth examination of morphological, anatomical, biochemical, molecular and gene expression levels enables plant scientists to identify the different pathways and signaling cascades involved in stress response. This timely book: * Covers a wide range of abiotic stresses in multiple plant species * Provides researchers and scientists with transgenic strategies to overcome stress tolerances in several plant species * Compiles the most recent research and up-to-date data on stress tolerance * Examines both selective breeding and genetic engineering approaches to improving plant stress tolerances * Written and edited by prominent scientists and researchers from across the globe Molecular Plant Abiotic Stress: Biology and Biotechnology is a valuable source of information for students, academics, scientists, researchers, and industry professionals in fields including agriculture, botany, molecular biology, biochemistry and biotechnology, and plant physiology.
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Table of Contents
Cover
List of Contributors
1 Plant Tolerance to Environmental Stress: Translating Research from Lab to Land
1.1 Introduction
1.2 Drought Tolerance
1.3 Cold Tolerance
1.4 Salinity Tolerance
1.5 Need for More Translational Research
1.6 Conclusion
References
2 Morphological and Anatomical Modifications of Plants for Environmental Stresses
2.1 Introduction
2.2 Drought‐induced Adaptations
2.3 Cold‐induced Adaptations
2.4 High Temperature‐induced Adaptations
2.5 UV‐B‐induced Morphogenic Responses
2.6 Heavy Metal‐induced Adaptations
2.7 Roles of Auxin, Ethylene, and ROS
2.8 Conclusion
References
3 Stomatal Regulation as a Drought‐tolerance Mechanism
3.1 Introduction
3.2 Stomatal Morphology
3.3 Stomatal Movement Mechanism
3.4 Drought Stress Sensing
3.5 Drought Stress Signaling Pathways
3.6 Mechanisms of Plant Response to Stress
3.7 Stomatal Density Variation in Response to Stress
3.8 Conclusion
References
4 Antioxidative Machinery for Redox Homeostasis During Abiotic Stress
4.1 Introduction
4.2 Reactive Oxygen Species
4.3 Antioxidative Defense System in Plants
4.4 Redox Homeostasis in Plants
4.5 Conclusion
References
5 Osmolytes and their Role in Abiotic Stress Tolerance in Plants
5.1 Introduction
5.2 Osmolyte Accumulation is a Universally Conserved Quick Response During Abiotic Stress
5.3 Osmolytes Minimize Toxic Effects of Abiotic Stresses in Plants
5.4 Stress Signaling Pathways Regulate Osmolyte Accumulation Under Abiotic Stress Conditions
5.5 Metabolic Pathway Engineering of Osmolyte Biosynthesis Can Generate Improved Abiotic Stress Tolerance in Transgenic Crop Plants
5.6 Conclusion and Future Perspectives
Acknowledgements
References
6 Elicitor‐mediated Amelioration of Abiotic Stress in Plants
6.1 Introduction
6.2 Plant Hormones and Other Elicitor‐mediated Abiotic Stress Tolerance in Plants
6.3 PGPR‐mediated Abiotic Stress Tolerance in Plants
6.4 Signaling Role of Nitric Oxide in Abiotic Stresses
6.5 Future Goals
6.6 Conclusion
References
7 Role of Selenium in Plants Against Abiotic Stresses: Phenological and Molecular Aspects
7.1 Introduction
7.2 Se Bioaccumulation and Metabolism in Plants
7.3 Physiological Roles of Se
7.4 Se Ameliorating Abiotic Stresses in Plants
7.5 Conclusion
7.6 Future Perspectives
References
8 Polyamines Ameliorate Oxidative Stress by Regulating Antioxidant Systems and Interacting with Plant Growth Regulators
8.1 Introduction
8.2 PAs as Cellular Antioxidants
8.3 The Relationship Between PAs and Growth Regulators
8.4 Conclusion and Future Perspectives
Acknowledgments
References
9 Abscisic Acid in Abiotic Stress‐responsive Gene Expression
9.1 Introduction
9.2 Deep Evolutionary Roots
9.3 ABA Chemical Structure, Biosynthesis, and Metabolism
9.4 ABA Perception and Signaling
9.5 ABA Regulation of Gene Expression
9.6 Post‐transcriptional and Post‐translational Control in Regulating ABA Response
9.7 Epigenetic Regulation of ABA Response
9.8 Conclusion
References
10 Abiotic Stress Management in Plants: Role of Ethylene
10.1 Introduction
10.2 Ethylene: Abundance, Biosynthesis, Signaling, and Functions
10.3 Abiotic Stress and Ethylene Biosynthesis
10.4 Role of Ethylene in Photosynthesis Under Abiotic Stress
10.5 Role of Ethylene on ROS and Antioxidative System Under Abiotic Stress
10.6 Conclusion
References
11 Crosstalk Among Phytohormone Signaling Pathways During Abiotic Stress
11.1 Introduction
11.2 Phytohormone Crosstalk Phenomenon and its Necessity
11.3 Various Phytohormonal Crosstalk Under Abiotic Stresses for Improving Stress Tolerance
11.4 Conclusion and Future Directions
Acknowledgements
References
12 Plant Molecular Chaperones: Structural Organization and their Roles in Abiotic Stress Tolerance
12.1 Introduction
12.2 Classification of Plant HSPs
12.3 Regulation of HSP Expression in Plants
12.4 Crosstalk Between HSP Networks to Provide Tolerance Against Abiotic Stress
12.5 Genetic Engineering of HSPs for Abiotic Stress Tolerance in Plants
12.6 Conclusion
Acknowledgements
References
13 Chloride (Cl
−
) Uptake, Transport, and Regulation in Plant Salt Tolerance
13.1 Introduction
13.2 Sources of Cl Ion Contamination
13.3 Role of Cl in Plant Growth and Development
13.4 Cl Toxicity
13.5 Interaction of Soil Cl with Plant Tissues
13.6 Electrophysiological Study of Cl Anion Channels in Plants
13.7 Channels and Transporters Participating in Cl Homeostasis
13.8 Conclusion and Future Perspectives
References
14 The Root Endomutualist
Piriformospora indica
: A Promising Bio‐tool for Improving Crops under Salinity Stress
14.1 Introduction
14.2
P. indica
: An Extraordinary Tool for Salinity Stress Tolerance Improvement
14.3 Utilization of
P. indica
for Improving and Understanding the Salinity Stress Tolerance of Host Plants
14.4
P. indica
‐induced Biomodulation in Host Plant under Salinity Stress
14.5 Activity of Antioxidant Enzymes and ROS in Host Plant During Interaction with
P. indica
14.6 Role of Calcium Signaling and MAP Kinase Signaling Combating Salt Stress
14.7 Effect of
P. indica
on Osmolyte Synthesis and Accumulation
14.8 Salinity Stress Tolerance Mechanism in Axenically Cultivated and Root Colonized
P. indica
14.9 Conclusion
Acknowledgments
Conflict of Interest
References
15 Root Endosymbiont‐mediated Priming of Host Plants for Abiotic Stress Tolerance
15.1 Introduction
15.2 Bacterial Symbionts‐mediated Abiotic Stress Tolerance Priming of Host Plants
15.3 AM Fungi‐mediated Alleviation of Abiotic Stress Tolerance of Vascular Plants
15.4 Other Beneficial Fungi and their Importance in Abiotic Stress Tolerance Priming of Plants
15.5 Implication of Transgenes from Symbiotic Microorganisms in the Era of Genetic Engineering and Omics
15.6 Conclusion and Future Perspectives
Acknowledgements
References
16 Insight into the Molecular Interaction Between Leguminous Plants and Rhizobia Under Abiotic Stress
16.1 Introduction
16.2 Legume–
Rhizobium
Interaction Chemistry: A Brief Overview
16.3 Role of Abiotic Stress Factors in Influencing Symbiotic Relations of Legumes
16.4 Conclusion: The Lessons Unlearnt
References
17 Effect of Nanoparticles on Oxidative Damage and Antioxidant Defense System in Plants
17.1 Introduction
17.2 Engineered Nanoparticles in the Environment
17.3 Nanoparticle Transformations
17.4 Plant Response to Nanoparticle Stress
17.5 Generation of Reactive Oxygen Species (ROS)
17.6 Nanoparticle Induced Oxidative Stress
17.7 Antioxidant Defense System in Plants
17.8 Conclusion
References
18 Marker‐assisted Selection for Abiotic Stress Tolerance in Crop Plants
18.1 Introduction
18.2 Reaction of Plants to Abiotic Stress
18.3 Basic Concept of Abiotic Stress Tolerance in Plants
18.4 Genetics of Abiotic Stress Tolerance
18.5 Fundamentals of Molecular Markers and Marker‐assisted Selection
18.6 Marker‐assisted Selection for Abiotic Stress Tolerance in Crop Plants
18.7 Marker‐assisted Selection for Drought Tolerance
18.8 Outlook
References
19 Transgenes: The Key to Understanding Abiotic Stress Tolerance in Rice
19.1 Introduction
19.2 Drought Effects in Rice Leaves
19.3 Molecular Analysis of Drought Stress Response
19.4 Omics Approach to Analysis of Drought Response
19.5 Plant Breeding Techniques to Improve Rice Tolerance
19.6 Marker‐assisted Selection
19.7 Transgenic Approach: Present Status and Future Prospects
19.8 Looking into the Future for Developing Drought‐tolerant Transgenic Rice Plants
19.9 Salinity Stress in Rice
19.10 Candidate Genes for Salt Tolerance in Rice
19.11 QTL Associated with Rice Tolerance to Salinity Stress
19.12 The Saltol QTL
19.13 Conclusion
References
20 Impact of Next‐generation Sequencing in Elucidating the Role of microRNA Related to Multiple Abiotic Stresses
20.1 Introduction
20.2 NGS Platforms and their Applications
20.3 Understanding the Small RNA Family
20.4 Criteria and Tools for Computational Classification of Small RNAs
20.5 Role of NGS in Identification of Stress‐regulated miRNA and their Targets
20.6 Conclusion
Acknowledgments
References
21 Understanding the Interaction of Molecular Factors During the Crosstalk Between Drought and Biotic Stresses in Plants
21.1 Introduction
21.2 Combined Stress Responses in Plants
21.3 Combined Drought–Biotic Stresses in Plants
21.4 Varietal Failure Against Multiple Stresses
21.5 Transcriptome Studies of Multiple Stress Responses
21.6 Signaling Pathways Induced by Drought–Biotic Stress Responses
21.7 Conclusion
Acknowledgments
Conflict of Interest
References
Index
End User License Agreement
List of Tables
Chapter 1
Table 1.1 List of genes used to generate drought‐tolerant transgenic plants.
Table 1.2 List of genes used to generate salt‐tolerant transgenic plants.
Chapter 4
Table 4.1 Role of ROS as secondary messengers in several plant hormone responses...
Chapter 5
Table 5.1 Osmolytes and their role in abiotic stresses in crop plants.
Table 5.2 Utilization of the osmolyte production and accumulation pathway‐relate...
Chapter 6
Table 6.1 Role of plant growth‐promoting rhizobacteria (PGPR) in various abiotic...
Table 6.2 Role of PGPRs in various abiotic stresses.
Table 6.3 Role of sodium nitroprusside (SNP) in various abiotic stresses.
Chapter 9
Table 9.1 Examples of genes coding for transcription factors (TFs) and their act...
Chapter 12
Table 12.1 Summary of molecular size, existing members, cellular location and fu...
Table 12.2 Summary of different classes of HSP overexpression in plants (recentl...
Chapter 13
Table 13.1 Source of contamination, roles, deficiency, and toxicity cause owing ...
Chapter 14
Table 14.1
Piriformospora indica
‐induced accumulation of osmolytes in host plant ...
Table 14.2 HOG1 pathway homologs in
P. indica
genome and similarity to yeast memb...
Table 14.3 HOG pathway‐regulated putative salinity stress responsive transcripti...
Chapter 17
Table 17.1 Reactive oxygen species (ROS) scavenging system in plants.
Chapter 19
Table 19.1 Candidate genes involved in rice response to salinity stress.
Table 19.2 QTL involved in rice response to salinity stress.
Chapter 20
Table 20.1 Comparison of some commonly used sequencing platforms.
Table 20.2 Comparison of some commonly used Illumina sequencing platforms.
Table 20.3 Comparative account of biogenesis and function of different small RNA...
Table 20.4 List of available tools or software for pre‐processing the NGS data.
Table 20.5 A list of major softwares or resources and repositories available for...
Table 20.6 List of tools used for prediction of isomiRs and siRNAs.
List of Illustrations
Chapter 1
Figure 1.1 Abiotic stress impact and plant responses (Lokhande et al. 2...
Chapter 2
Figure 2.1 Environmental factors which affect plants.
Figure 2.2 Plant responses against different environmental stresses.
Chapter 3
Figure 3.1 A schematic representation of drought stress signal percepti...
Chapter 4
Figure 4.1 Various factors responsible for generation of reactive oxyge...
Figure 4.2 Energy transfer pathway for generation of ROS.
Figure 4.3 ROS generation sites in plants.
Figure 4.4 Impact of ROS on lipids, proteins, and DNA under oxidative d...
Chapter 5
Figure 5.1 Schematic representation of overall relation between abiotic...
Figure 5.2 Regulation of osmolyte production and accumulation upon perc...
Chapter 6
Figure 6.1 Role of nitric oxide (NO) in plant system. (1) It breaks see...
Chapter 7
Figure 7.1 Se metabolism within plant cells. APS, ATP sulfurylase; APR,...
Figure 7.2 Se alleviates oxidative stresses in plants by efficiently ac...
Chapter 9
Figure 9.1 Regulation of the plant abiotic stress response modulated by...
Chapter 11
Figure 11.1 Phytohormonal crosstalks in abiotic stress environment. Upo...
Chapter 12
Figure 12.1 Structural organization and mode of action of small heat sh...
Figure 12.2 Structural organization and mode of action of HSP60: (a) do...
Figure 12.3 Structural organization and mode of action of HSP70: (a) do...
Figure 12.4 Domain organization of HSP40.
Figure 12.5 Structural organization and mode of action of HSP90: (a) do...
Figure 12.6 Structural organization and mode of action of HSP100: (a) d...
Chapter 13
Figure 13.1 Diagrammatic presentation of channels and transporters asso...
Figure 13.2 SLAC/SLAH phylogenetic tree. The dendrogram indicates the d...
Figure 13.3 Aluminum‐activated malate transporter (ALMT) channel phylog...
Figure 13.4 CLC channel phylogenetic tree shows four clades. The dendro...
Figure 13.5 Possible molecular mechanisms of Cl
−
influx, efflux, ...
Chapter 14
Figure 14.1 Osmolyte accumulation in host plants during
Piriformospora
...
Figure 14.2 Association of
P. indica
with host plant root for improving...
Chapter 15
Figure 15.1 Overview of symbiosis associated priming of a plant cell fo...
Chapter 16
Figure 16.1 Integrated schematic diagram showing the molecular events o...
Chapter 17
Figure 17.1 Illustration of the dynamic transformations that nanopartic...
Figure 17.2 Metabolic pathway of reactive oxygen species in plants.
Chapter 18
Figure 18.1 Molecular marker‐based strategies on screening and subseque...
Chapter 20
Figure 20.1 Schematic representation of the various next generation seq...
Figure 20.2 Schematic representation of small RNA sample preparation.
Figure 20.3 Graphical representation of the usage of various sequencing...
Figure 20.4 Schematic representation to show the steps in biogenesis of...
Chapter 21
Figure 21.1 Potential responses of plant exposed to drought–biotic stre...
Figure 21.2 Key events in the signaling pathway activated during plant'...
Figure 21.3 The schematic representation of crosstalk between hormones,...
Guide
Cover
Table of Contents
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Molecular Plant Abiotic Stress
Biology and Biotechnology
Edited by
Dr Aryadeep Roychoudhury
Department of BiotechnologySt. Xavier's College (Autonomous)30, Mother Teresa SaraniKolkata-700016,West BengalIndia
Dr Durgesh Kumar Tripathi
Amity Institute of Organic AgricultureAmity University, Uttar PradeshI 2 Block, 5th Floor, AUUP Campus Sector-125Noida-201313, Uttar PradeshIndia
Copyright
This edition first published 2019
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Library of Congress Cataloging‐in‐Publication Data
Names: Roychoudhury, Aryadeep, editor. Tripathi, Durgesh Kumar, editor.
Title: Molecular plant abiotic stress : biology and biotechnology / edited by
Dr. Aryadeep Roychoudhury, Department of Biotechnology, St. Xavier's
College, Bengal, India, Dr. Durgesh Kumar Tripathi, Amity Institute of
Organic Agriculture (AIOA), Amity University, Noida, India.
Description: First edition. | Hoboken, NJ : Wiley, 2019. | Includes bibliographical references and index. |
Identifiers: LCCN 2019011920 (print) | LCCN 2019012932 (ebook) | ISBN 9781119463689 (Adobe PDF) | ISBN 9781119463672 (ePub) | ISBN 9781119463696 (hardback)
Subjects: LCSH: Plants–Effect of stress on–Molecular aspects. | Plant molecular biology. | Plant physiology. | Plants–Adaptation.
Classification: LCC QK754 (ebook) | LCC QK754 .M65 2019 (print) | DDC 572.8/2928–dc23
LC record available at https://lccn.loc.gov/2019011920
Cover Design: Wiley
Cover Image: © Jose A. Bernat Bacete/Getty Images
List of Contributors
Krishnendu Acharya
Department of Botany
University of Calcutta
Kolkata, West Bengal
India
Nimisha Amist
Plant Physiology Laboratory
Department of Botany
University of Allahabad
Allahabad, 211002
India
Aditi Shreeya Bali
Department of Botany
M.C.M. DAV College for Women
Chandigarh, 160036
India
Aditya Banerjee
Department of Biotechnology
St. Xavier's College (Autonomous)
Kolkata, West Bengal
India
Chanda Bano
Plant Physiology Laboratory
Department of Botany
University of Allahabad
Allahabad, 211002
India
Supratim Basu
NMC Biolab
New Mexico Consortium
Los Alamos, New Mexico
USA
Renu Bhardwaj
Plant Stress Physiology Lab
Department of Botanical & Environmental Sciences
Guru Nanak Dev University
Amritsar, 143005
India
Deepa Bisht
School of Life Sciences
Jawaharlal Nehru University
New Delhi
India
Dipankar Chakraborti
Department of Biotechnology
St. Xavier's College (Autonomous)
30, Mother Teresa Sarani
Kolkata, 700016, West Bengal
India
Nilanjan Chakraborty
Department of Botany
Scottish Church College
Kolkata, West Bengal
India
Rituparna Kundu Chaudhuri
Department of Botany
Krishnagar Govt. College
Krishnagar, 741101, West Bengal
India
Francinilson Meireles Coelho
Universidade Federal do Pará
Belém, PA
Brazil
Solange da Cunha Ferreira
Universidade Federal do Pará
Belém, PA
Brazil
Prabal Das
Department of Botany
University of Calcutta
Kolkata, West Bengal
India
Sampa Das
Division of Plant Biology
Bose Institute, P1/12, CIT Scheme, VIIM
Kolkata, West Bengal
India
Meenakshi Dua
School of Environmental Sciences
Jawaharlal Nehru University
New Delhi, 110067
India
Shreeparna Ganguly
Department of Biotechnology
St. Xavier's College (Autonomous)
30, Mother Teresa Sarani
Kolkata, 700016, West Bengal
India
Saikat Gantait
Department of Genetics and Plant Breeding
Faculty of Agriculture
Bidhan Chandra Krishi Viswavidyalaya
Mohanpur, Nadia, West Bengal, 741252
India
Budhayash Gautam
Sam Higginbottom University of Agriculture, Technology and Sciences
Allahabad, Uttar Pradesh
India
S. B. Ghag
School of Biological Sciences
UM‐DAE Centre for Excellence in Basic Sciences
Kalina campus, Santacruz (East)
Mumbai, Maharashtra
India
Kavita Goswami
International Centre for Genetic Engineering and Biotechnology
New Delhi
India
Sumanti Gupta
Department of Botany
Rabindra Mahavidyalaya
Hooghly, West Bengal
India
Varsha Gupta
National Institute of Plant Genome Research
New Delhi
India
Shokoofeh Hajihashemi
Plant Biology Department
Behbahan Khatam Alanbia University of Technology
Khuzestan
Iran
Abhimanyu Jogawat
National Institute of Plant Genome Research
New Delhi
India
Atul Kumar Johri
School of Life Sciences
Jawaharlal Nehru University
New Delhi
India
Dhriti Kapoor
School of Bioengineering & Biosciences
Lovely Professional University
Punjab, 144411
India
PB Kavi Kishor
Center for Biotechnology
Acharya Nagarjuna University
Guntur, 522510
India
Kanika Khanna
Plant Stress Physiology Lab
Department of Botanical & Environmental Sciences
Guru Nanak Dev University
Amritsar, 143005
India
Sukhmeen Kaur Kohli
Plant Stress Physiology Lab
Department of Botanical & Environmental Sciences
Guru Nanak Dev University
Amritsar, 143005
India
Anil Kumar
School of Biotechnology
Shri Mata Vaishno Devi University
Katra, J&K
India
Rakesh Kumar
Department of Botany
DAV University
Sarmastpur, Jalandhar, 144012, Punjab
India
Sandeep Kumar
Department of Environmental Sciences
DAV University
Sarmastpur, Jalandhar, 144012, Punjab
India
Vinod Kumar
Department of Botany
DAV University
Sarmastpur, Jalandhar, 144012, Punjab
India
P Maheshwari
Center for Biotechnology
Acharya Nagarjuna University
Guntur, 522510
India
Sharada Mallubhotla
School of Biotechnology
Faculty of Sciences
Shri Mata Vaishno Devi University
Katra, 182320, J&K
India
Deyvid Novaes Marques
Universidade Federal do Pará
Belém, PA
Brazil
Joseph Msanne
NMC Biolab
New Mexico Consortium
Los Alamos, New Mexico
USA
GC Nikalje
Department of Botany
Savitribai Phule Pune University
Pune, 411007
India
TD Nikam
Department of Botany
Savitribai Phule Pune University
Pune, 411007
India
Lymperopoulos Panagiotis
NMC Biolab
New Mexico Consortium
Los Alamos, New Mexico
USA
Manoj Prasad
National Institute of Plant Genome Research
New Delhi
India
DL Punita
Center for Biotechnology
Acharya Nagarjuna University
Guntur, 522510
India
Arnab Purohit
Department of Biotechnology
St. Xavier's College (Autonomous)
30, Mother Teresa Sarani
Kolkata, West Bengal
India
Roel Rabara
NMC Biolab
New Mexico Consortium
Los Alamos, New Mexico
USA
KRSS Rao
Center for Biotechnology
Acharya Nagarjuna University
Guntur, 522510
India
Sávio Pinho dos Reis
Universidade Federal do Pará
Belém, PA
Brazil
Aryadeep Roychoudhury
Department of Biotechnology
St. Xavier's College (Autonomous)
30, Mother Teresa Sarani
Kolkata, West Bengal
India
Neeti Sanan‐Mishra
International Centre for Genetic Engineering and Biotechnology
New Delhi
India
Anik Sarkar
Department of Botany
University of Calcutta
Kolkata, West Bengal
India
Sutanu Sarkar
Department of Genetics and Plant Breeding
Faculty of Agriculture
Bidhan Chandra Krishi Viswavidyalaya
Mohanpur, Nadia, West Bengal, 741252
India
Babar Shahzad
School of Land and Food
University of Tasmania
Hobart, Tasmania
Australia
Anket Sharma
Plant Stress Physiology Lab
Department of Botanical & Environmental Sciences
Guru Nanak Dev University
Amritsar, 143005
India
Savita Sharma
School of Biotechnology
Shri Mata Vaishno Devi University
Katra, J&K
India
DB Shelke
Department of Botany
Savitribai Phule Pune University
Pune, 411007
India
Gagan Preet Singh Sidhu
Department of Applied Sciences
UIET
Chandigarh, 160014
India
N. B. Singh
Department of Botany
University of Allahabad
Allahabad, Uttar Pradesh
India
Roshan Kumar Singh
National Institute of Plant Genome Research
New Delhi
India
Vivek K. Singh
School of Physics
Shri Mata Vaishno Devi University
Katra, J&K
India
Cláudia Regina Batista de Souza
Universidade Federal do Pará
Belém, PA
Brazil
P. Suprasanna
Nuclear Agriculture and Biotechnology Division
Bhabha Atomic Research Centre
Trombay, Mumbai, Maharashtra
India
Eraldo José Madureira Tavares
Empresa Brasileira de Pesquisa Agropecuária
Petrolina, PE
Brazil
Liliane Souza Conceição Tavares
Universidade Federal do Pará
Belém, PA
Brazil
Ashwani Kumar Thukral
Plant Stress Physiology Lab
Department of Botanical & Environmental Sciences
Guru Nanak Dev University
Amritsar, 143005
India
Anita Tripathi
International Centre for Genetic Engineering and Biotechnology
New Delhi
India
Durgesh Kumar Tripathi
Amity Institute of Organic Agriculture
Amity University, Uttar Pradesh
I 2 Block, 5th Floor, AUUP Campus Sector‐125
Noida, 201313, UP
India
Nidhi Verma
School of Life Sciences
Jawaharlal Nehru University
New Delhi, 110067
India
Sandeep Kumar Verma
Institute of Biological Science
SAGE University
Kailod Kartal, Indore
Madhya Pradesh, 452020
India
Poonam Yadav
Plant Stress Physiology Lab
Department of Botanical & Environmental Sciences
Guru Nanak Dev University
Amritsar, 143005
India
1Plant Tolerance to Environmental Stress: Translating Research from Lab to Land
P. Suprasanna1 and S. B. Ghag2
1Nuclear Agriculture and Biotechnology Division, Bhabha Atomic Research Centre, Trombay, 400 085 Mumbai, India
2Department of Biology, UM‐DAE Centre for Excellence in Basic Sciences, Kalina campus, Santacruz (East), Mumbai 400 098, India
3Homi Bhabha National Institute, Mumbai, 400 095, India
1.1 Introduction
Food security for a burgeoning human population in a sustainable ecosystem is an important goal. However, the threat from climate change and unpredictable environmental extremes (Abberton et al. 2016) to plant growth and productivity (Lobell and Gourdji 2012; Gray and Brady 2016; Tripathi et al. 2016a) is increasing. Climate change‐driven effects, especially from erratic environmental fluctuations, can result in increased prevalence of abiotic stresses and, pests and pathogens in crop plants (Chakraborty and Newton 2011; Batley and Edwards 2016). Various abiotic stresses such as drought, salinity, temperature, and heavy metals have been shown to diminish average yields by more than 50% for major crops (Wang et al. 2003; Pereira 2016; Tripathi et al. 2016c).
Over the years, considerable information has become available on the stress‐related genetic repertoire of genes, quantitative trait loci and molecular networks governing plant responses to drought, salinity, heat, and other abiotic stresses (Krasensky and Jonak 2012; Liu et al. 2018). This knowhow about genes and their regulation will enable improvements in stress tolerance in crops, in the face of the imminent threat of climate change, impacting crop genetic diversity and the productivity of staple food crops. Global temperature rises of 2–3 °C are predicted to push crops toward extinction and even wild species that have so far been considered valuable genetic resource may also be affected. This will have negative consequences locally as well as globally, because the key traits for adaptiveness to climate change and variability adaptation may be lost forever. It is hence desirable that additional genetic variability should be introduced through mutagenesis or other approaches. Over the past few decades, great success has been achieved through selection, breeding, hybridization, recombination, and mutation to broaden genetic variability for important traits conferring adaptation of many species to changing biotic, climatic, and environmental pressures.
Crop plants are susceptible to climate‐driven abiotic (elevated CO2, heat, drought, salinity, flooding) and biotic effects (Chapman et al. 2012). Several reviews have critically discussed the impact of climate change on various crop systems (Ahuja et al. 2010; Yadav et al. 2011; Tripathi et al. 2016a). Abiotic stresses elicit a plethora of morphological, physiological, biochemical, and molecular alterations (Singh et al. 2015a,b; Tripathi et al. 2016b, 2017; Singh et al. 2017; Suprasanna et al. 2018). The impact of stress has been shown to induce modulated gene function of structural genes, regulatory genes, and other master regulators (Zhu 2016; Patel et al. 2018). Plant defenses are endowed with molecular components of stress signal perception, osmotic and ionic homeostasis, hormone signaling, reactive oxygen species (ROS) scavenging systems, metabolic pathways, etc. (Figure 1.1). There are specific responses that are osmotic, hormonal, ionic, signal transduction, and transcription factor based, and there are also nonspecific responses that are activated by ROS (Mittler and Blumwald 2010, Muchate et al. 2016). Despite tremendous knowledge that has been generated in understanding abiotic stress responses, an integrated information gateway is needed to combine all of the genomics, proteomics, and metabolomics data concerning field conditions to achieve plant tolerance of environmental change (Roychoudhury et al. 2011, Edwards 2016). This has become a challenge that requires concerted effort. Hirayama and Shinozaki (2010) outlined some considerations (see Box 1.1) which should pave the way toward achieving this goal.
Figure 1.1 Abiotic stress impact and plant responses (Lokhande et al. 2012).
Box 1.1
Sensor(s) and signaling pathways – perception and transduction of local stress signals under single and combined stresses.
Molecular basis of interaction among biotic and abiotic stresses.
Key factors in the crosstalk between abiotic stress responses and other plant developmental pathways.
Long‐term stress‐associated responses under multiple abiotic stress conditions.
Experimental conditions that simulate natural field conditions for testing and functional validation.
Modified after Hirayama and Shinozaki ( 2010).
Research into plant abiotic stress biology has two dimensions: the first, is the need to develop a detailed mechanistic view of plant responses to single and/or combined stresses to create a resource of gene targets and regulatory circuits for the improvement of stress‐tolerant crop plants; and the second is the translation of research outcome into environmentally challenging field conditions. Physiological, biochemical, and molecular studies have generated data and great understanding of the mechanisms of how a plant will respond to a given stress or combined stress factors. Transcriptomic studies have demonstrated that the adaptation or responses are controlled by either up‐ or down‐regulation of several genetic pathways and processes associated with stress perception and signaling (Munns and Tester 2008; Roychoudhury and Banerjee 2015). Transgenic approaches are available as the existing strategies for crop improvement programs based on biotechnology (Jewell et al. 2010). Genetic engineering for improved stress tolerance has been made possible through the manipulation of a single or a few effector genes or regulatory genes (Wang et al. 2016) or those that encode osmolytes, antioxidants, chaperones, water, and ion transporters (Chen et al. 2014; Paul and Roychoudhury 2018; Suprasanna et al. 2018). Various genes involved in the synthesis of osmoprotectants have been explored for their potential in improving abiotic stress tolerance (Reguera et al. 2012). In this article, we have reviewed the progress made in genetic engineering for abiotic stress tolerance, especially drought, salinity and cold, and highlight the potential areas for translational research in this field.
1.2 Drought Tolerance
Paucity of water is the most important environmental stress affecting crop plants, accounting for ∼70% loss of potential yield worldwide (Shiferaw et al. 2014). Daryanto et al. (2016) investigated the data published from 1980 to 2015 that reported up to 21% and 40% yield reductions in wheat and maize, respectively, owing to drought worldwide. With changing climatic conditions and limited water supply, it is necessary to develop crop plants that can sustain drought conditions without reduced yield. Moreover, much lands are left barren due to poor water supply. Generating plants that can withstand drought stress will improve the food security for the growing population. Understanding of the physiological and biochemical basis of drought response and the gene regulatory networks relating to drought tolerance in plants is necessary. Remarkable studies have been carried out that identify the key regulators of drought response at different stages. These can be classified as: (i) drought induced transcriptional factors such as dehydration‐responsive‐element‐bindings (DREBs), abscisic acid responsive element binding proteins (AREBs)/abscisic acid responsive element binding factors (ABFs), nuclear factor Y‐B subunits (NF‐YB), and tryptophan–arginine–lysine–tyrosine (WRKY) (Oh et al. 2005; Nelson et al. 2007; Xiao et al. 2009; Wu et al. 2009; Banerjee and Roychoudhury 2015); (ii) posttranscriptional and/or posttranslational modifications (Wang et al. 2008; Xiang et al. 2007; Kim et al. 2017); and (iii) production of osmoprotectant and molecular chaperones (Xiao et al. 2009; Bhaskara et al. 2015; Liu et al. 2015). Overexpressing or downregulating drought‐responsive genes has yielded success in the laboratory. However, field studies demonstrating drought tolerance in plants are required to confirm the results.
Drought stress induces the synthesis or transportation of the phytohormone abscisic acid (ABA), which is a key molecule regulating signal events during drought impact (Fang and Xiong 2015). The initial perception of accumulation of ABA is through a complex of PYR (pyrabactin resistance)/PYL (PYR1‐like)/RCARb (regulatory component of abscisic acid response), PP2C (protein phosphatase 2C), and SnRK2 (sucrose nonfermenting1‐related protein kinase 2), which induces the expression of transcription factors NF‐YA, SNAC (stress and abscisic acid‐Inducible NAC), and AREBs (Roychoudhury and Paul 2012). These proteins further regulate the opening and closing of stomata to reduce transpirational water loss. Drought stress is also perceived by another regulatory loop through calcium‐dependent protein kinase (CDPK) and calcineurin B‐like protein‐interacting protein kinase (CIPK), which activates AREB and DREBs that bind to the dehydration responsive element and abscisic acid responsive element cis‐elements of downstream genes to produce the effector proteins such as late embryogenesis abundant protein (LEA), heat‐shock protein (HSP), proline, glycine betaine, sugars, and polyamines (Yang et al. 2010). The overexpression of these transcription factors in drought‐sensitive plants has improved tolerance of water‐deficit conditions (Table 1.1). Moreover, some plants constitutively expressing drought‐responsive transcription factors displayed growth retardation (Suo et al. 2012). To lessen this undesirable effect, researchers have employed stress‐inducible promoters such as HVA22P to drive the expression of these transgenes in transgenic plants (Bhatnagar‐Mathur et al. 2007; Xiao et al. 2009). However, when the drought stress is extended, it induces continuous expression of these genes in the transgenic plants, resulting in growth anomalies. To circumvent this problem, researchers have used stress‐inducible tissue‐specific promoters such as Responsive To Dehydration 29A (RD29A) for expressing these transgenes (Ito et al. 2006; Kasuga 2004). RD29A promoter is expressed only in the root tissues of rice plants under abiotic stress conditions. However, a small problem in root development could circumvent its use. To address this problem, Kudo et al. (2016) stacked two transcription factors in transgenic Arabidopsis plants, namely DREB1A to improve drought tolerance and the rice Phytochrome‐Interacting Factor‐Like 1 (OsPIL1) to partially enhance plant growth. OsPIL1 augments cell elongation by regulating cell wall‐related gene expression, thereby circumventing the negative effects of overexpression of DREB1A gene. All of these individual strategies can be grouped together, wherein the gene‐stacking strategy can be employed along with the use of stress‐inducible tissue‐specific promoters to impart drought tolerance and at the same time remove the growth‐retardation effects. The strategy will be more effective and acceptable if the genes and promoters are chosen from a plant and overexpressed in the same plant.
Table 1.1 List of genes used to generate drought‐tolerant transgenic plants.
Target gene
Source of gene
Target plant
Evaluation
Functional change
References
AtABF3
Arabidopsis thaliana
Oryza sativa
cv. Nakdong
Greenhouse
No visible growth abnormality, increased drought tolerance
Oh et al.
2005
SNAC1
Rice IRAT109
Rice (japonica)
Greenhouse, field
No growth anomaly, drought tolerance
Hu et al.
2006
OsNAC6
Rice cv. Nipponbare
Rice cv. Nipponbare
Greenhouse
Growth retardation, poor reproductive yields, increased tolerance to dehydration and enhanced resistance to blast disease
Nakashima et al.
2007
DREB1A
Arabidopsis thaliana
Triticum aestivum
Greenhouse
Delayed drought symptoms
Pellegrineschi et al.
2004
Arabidopsis thaliana
Arachis hypogaea
L. cv. JL 24
Greenhouse
40% higher transpiration efficiency than the untransformed controls
Bhatnagar‐Mathur et al.
2007
OsDREB1G
Oryza sativa
L. ssp
. japonica
cv. Zhonghua 11
Oryza sativa
L. ssp
. japonica
cv. Zhonghua 11
Greenhouse
Improved tolerance to drought stress
Chen et al.
2008
OsDREB2B
Oryza sativa
L. ssp
. japonica
cv. Zhonghua 11
Oryza sativa
L. ssp
. japonica
cv. Zhonghua 11
Greenhouse
Improved tolerance to water deficit stress
Chen et al.
2008
OsDREB1F
Oryza sativa
Oryza sativa
and
Arabidopsis
Greenhouse
Enhanced tolerance to salt, drought, and low temperature
Wang et al.
2008
GhDREB
Gossypium hirsutum
Triticum aestivum
L.
Greenhouse
Improved tolerance to drought, salt, and freezing stresses, increased accumulation of soluble sugar and chlorophyll in leaves under stress conditions
Gao et al.
2009
HhDREB2
Halimodendron
halodendron
Arabidopsis
Greenhouse
Increased tolerance to salt and drought stresses
Ma et al.
2015
GmDREB2
Glycine max
L.
Arabidopsis
and tobacco
Greenhouse
Enhanced tolerance to drought and high‐salt stresses, high proline levels
AtDREB2A‐CA
Arabidopsis thaliana
Gossypium hirsutum
L.
Greenhouse
Improved shoot development, improved morphometrics roots traits under water deficit
Lisei‐de‐Sá et al.
2017
HARDY
Arabidopsis
O.
sativa
ssp. Japonica cv. Nipponbare
Greenhouse
Increased leaf biomass and bundle sheath cells, enhanced photosynthesis assimilation
Karaba et al.
2007
Arabidopsis
Trifolium alexandrinum
L.
Greenhouse, field
Thicker stems and more xylem rows per vascular bundle, resistant to lodging in the field, drought tolerance
Abogadallah et al.
2011
ZFP252
Oryza sativa
L. cv.
Zhonghua 11
Oryza sativa
L. cv.
Zhonghua 11
Greenhouse
Increased amount of free proline and soluble sugars, high‐level expression of stress defense genes and enhanced rice tolerance to salt and drought stresses
Xu et al. 2008
ZFP182
Oryza sativa
L.
subs. Japonica
cv.
Zhonghua 11
Oryza sativa
L.
subs. Japonica
cv.
Zhonghua 11
Greenhouse
Increased accumulation of free proline and soluble sugars
Huang et al.
2012
DST
Oryza sativa
L. cv.
Zhonghua 11
Oryza sativa
L. cv.
Zhonghua 11
Greenhouse
Enhanced drought and salt tolerance in rice
Huang et al.
2009
ZAT10
Arabidopsis thaliana
Oryza sativa
L. ssp. Japonica
Greenhouse, field
High spikelet fertility and high yield under drought stress
Xiao et al.
2009
NHX1
Arabidopsis thaliana
Oryza sativa
L. ssp. Japonica
Greenhouse, field
High spikelet fertility and high yield under drought stress
Xiao et al.
2009
LOS5
Arabidopsis thaliana
Oryza sativa
L. ssp. Japonica
Greenhouse, field
High spikelet fertility and high yield under drought stress
Xiao et al.
2009
Arabidopsis thaliana
Nicotiana tabacum
Greenhouse
Higher water content, better cellular membrane integrity, accumulated higher quantities of ABA and proline, and higher levels of antioxidant enzymes
Yue et al.
2011
Arabidopsis thaliana
Maize
Greenhouse
Reductions in stomatal aperture, higher relative water content and leaf water potential, lower leaf wilting, less electrolyte leakage, less malondialdehyde and H
2
O
2
content, and higher levels of antioxidative enzymes and proline content
Lu et al.
2013
NPK1
Arabidopsis thaliana
Oryza sativa
L. ssp. Japonica
Greenhouse, field
High spikelet fertility and high yield under drought stress
Xiao et al.
2009
LeNCED1
Tomato
Petunia
Greenhouse
Elevated leaf ABA concentrations, increased concentrations of proline, and increase in drought resistance.
Estrada‐Melo et al.
2015
AtNF‐YB1
Arabidopsis thaliana
Arabidopsis thaliana
Greenhouse
Higher water potential and photosynthesis rate
Nelson et al.
2007
ZmNF‐YB2
Zea mays
Maize
Greenhouse, field
Increased chlorophyll content, stomatal conductance, leaf temperature, reduced wilting, and maintenance of photosynthesis under stress conditions
Nelson et al.
2007
TaNF‐YB3
Triticum aestivum
Tobacco cv. Wisconsin 35
Greenhouse
Improved growth under drought, enhanced leaf water retention capacity, and increased antioxidant enzyme activities and osmolyte accumulation.
Yang et al.
2017
GmNFYB1
Glycine max
Arabidopsis
Greenhouse
Higher seed germination rate, longer root lengths, increased proline accumulation in leaves and decreased water loss under drought and salt stress conditions
Li et al.
2016
Cdt‐NF‐YC1
Bermuda grass
(Cynodon dactylon 9 Cynodon transvaalensis)
Oryza sativa
L. ssp
. japonica
cv. Zhonghua 11
Greenhouse
Increased tolerance to drought and salt stress and increased sensitivity to ABA
Chen et al.
2015a,b
OsWRKY11
Oryza sativa
L.
Oryza sativa
cv. Sasanishiki
Greenhouse
Slower leaf wilting and less impaired survival rate
Wu et al.
2009
PdNF‐YB7
Populus nigra × (Populus deltoides × Populus nigra)
Arabidopsis
Greenhouse
Increased seed germination rate and root length and decrease in water loss, and displayed higher photosynthetic rate
Han et al.
2013
DnWRKY11
Dendrobium nobile
Nicotiana tabacum
cv. Huangmiaoyu
Greenhouse
Higher germination rate, longer root length, higher fresh weight, higher activities of antioxidant enzymes, and lower content of malonidialdehyde
Xu et al.
2014
FcWRKY70
Fortunella crassifolia
Nicotiana nudicaulis
and
Citrus lemon
Greenhouse
Higher expression levels of arginine decarboxylase and accumulated larger amount of putrescine
Gong et al.
2015
TaWRKY33
T. aestivum
cv. Xiaobaimai
Arabidopsis
Greenhouse
Increased germination rates, promoted root growth and reduced water loss
He et al.
2016
FtbHLH3
Fagopyrum tataricum
Arabidopsis
Greenhouse
Lower malondialdehyde, ion leakage, and reactive oxygen species, higher proline content, activities of antioxidant enzymes, and increased photosynthetic efficiency
Yao et al.
2017
Musa DHN‐1
Musa
spp.
Musa
spp.
Greenhouse
Improved tolerance to drought and salt‐stress, increased accumulation of proline and reduced malondialdehyde levels
Shekhawat et al.
2011
AnnSp2
Solanum pennellii
Solanum lycopersicum
Greenhouse
Induced stomatal closure and reduced water loss, improved scavenging of ROS, higher total chlorophyll content, lower lipid peroxidation levels, increased peroxidase activities and higher levels of proline
Ijaz et al.
2017
SbPIP1
Salicornia bigelovii
Nicotiana tabacum
Greenhouse
Higher relative water content and proline content, but lower levels of malondialdehyde and less ion leakage
Sun et al.
2017a,b
DRIR
Arabidopsis thaliana
Arabidopsis thaliana
Greenhouse
Increased tolerance to drought and salt stress
Qin et al.
2017
Sly‐miR169c
Solanum lycopersicum
Solanum lycopersicum
Greenhouse
Reduced stomatal opening and transpiration rate, lowered leaf water loss, and enhanced drought tolerance
Zhang et al.
2011
miR408
Arabidopsis thaliana
Chickpea
Greenhouse
Stunted growth, regulation of
DREB
genes
Hajyzadeh et al.
2015
Post‐translational modification such as phosphorylation, farnesylation, sumoylation, and poly(ADP‐ribosyl)ation (PAR) of drought‐responsive proteins in the above regulatory network regulates drought stress tolerance (Wang et al. 2009; Xiang et al. 2007; Kim et al. 2017). Conditional and specific downregulation of farnesyl transferase gene in canola using the AtHPR1 promoter resulted in yield protection against drought stress under field conditions (Wang et al. 2009). Overexpression of protein kinases such as CDPKs and CIPKs in transgenic plants improved tolerance to drought stress (Saijo et al. 2000; Xiang et al. 2007; Vivek et al. 2013; Campo et al. 2014; Wei et al. 2014; Tai et al. 2016; Wang et al. 2018).
LEAs are hydrophilic proteins that usually accumulate in embryos during seed desiccation and are known to be involved in adaptive responses to dehydration by binding water molecules, stabilizing proteins or membrane structures and acting as molecular chaperones like HSPs (Bray 1997). The expression of LEA genes in transgenic plants displays increased ABA sensitivity and enhances osmotic tolerance (Duan and Cai 2012; Wang et al. 2014; Yu et al. 2016; Banerjee and Roychoudhury 2016). The accumulation of proline, glycine betaine, sugars like trehalose and polyamines like spermine, spermidine, and putrescine prevents water loss and protects the cellular components from osmotic damage (Zhu et al. 1998; Quan et al. 2004; Lv et al. 2007; Xiao et al. 2009; Bhaskara et al. 2015; Liu et al. 2015; Mwenye et al. 2016; Montilla‐Bascón et al. 2017; Liu et al. 2017; Juzoń et al. 2017). The overexpression of plant or bacterial cold shock proteins in major staple crops such as maize, rice, and wheat has conferred drought tolerance and increased yield under field conditions (Castiglioni et al. 2008; Yu et al. 2017). During stress conditions, modulation of cellular energy homeostasis is the key to improving plant performance and yield stability. Poly(ADP‐ribosyl)ation is a unique posttranslational protein modification (mediated by the PARP enzyme) induced in plants during environmental stress conditions. PAR is known to be involved in DNA synthesis and repair, transcription, and cell cycle activities (d'Amours et al. 1999). Inhibition of PARP activity alters photosynthesis and improves stress tolerance in plants (Vanderauwera et al. 2007; Schulz et al. 2012).
MicroRNAs and long noncoding RNAs have also been acknowledged in response to drought stress (Ferdous et al. 2015; Qin et al. 2017). Several miRNAs are up‐ or downregulated during drought stress (Ferdous et al. 2015; Shriram et al. 2016; Banerjee et al. 2016). These miRNAs can be targeted to generate transgenic plants using particular promoters. Overexpression of a rice Osa‐miR319a in transgenic creeping bentgrass (Agrostis stolonifera) displayed enhanced drought and salt tolerance. These plants showed increased leaf wax content and water retention but reduced sodium uptake (Zhou et al. 2013). Expression of miRNA408 in chickpea and miR169 in tomato showed enhanced drought tolerance in these plants (Zhang et al. 2011; Hajyzadeh et al. 2015). Advanced sequencing technologies are now available for deriving the genomic and transcriptomic information during drought tolerance which in turn could reveal the regulatory networks activated during drought (Huang et al. 2014; Chung et al. 2016; Muthusamy et al. 2016; Li et al. 2017a,b,c; Bai et al. 2017). Engineering the components of these regulatory networks will further help in developing better drought‐tolerant crops.
Since many of the studies carried out until now have been restricted to greenhouse or experimental fields, the tolerant plants should be tested for their full capacity under natural field conditions where other environmental factors accompany drought scenario. It is difficult to measure the performance of transgenic plants under drought conditions as drought is variable from mild to extreme and in duration. A drought‐tolerant transgenic maize line, DroughtGard™, developed by Monsanto, harbors the bacterial cspB gene which was commercialized in 2011 (Castiglioni et al. 2008). The credibility of the gene could not be fully validated during this study because of varying drought conditions along with variable ambient temperatures and soil conditions.The transgenic line displayed tolerance to moderate drought but could sustain extreme drought conditions (Gurian‐Sherman 2012). Bayer Crop Science also adopted the Performance Plants Inc. Yield Protection Technology for the development of drought‐tolerant and high‐yielding cotton in 2009. After repeated field trials for three consecutive years under natural field conditions, these cotton plants showed significant yield advantages under water stress and no undesirable effects on growth under optimal conditions (Performance Plants 2019).
1.3 Cold Tolerance
Cold stress is another critical abiotic stress agent that limits crop cultivation and restricts growth and development, hampering crop productivity. Cold tolerance is achieved through acclimation of the crop plants to lower temperatures (chilling temperatures, 0–15 °C) or even below‐freezing temperatures (<0 °C), which are associated with changes in the biochemical and physiological characteristics. Conventional breeding has gained limited success in achieving cold tolerance in crop plants owing to poor genetic variance and a restricted gene pool. Recent advances in high‐throughput technologies have helped in identifying genes and gene families responsive to chilling or freezing stress in plants. Further, transferring these genes through recombinant DNA technology has generated transgenic crops that are tolerant to cold stress.
Low temperatures prevent germination of seeds, decrease pollen fertility, seed set, and chlorophyll content and reduce photosynthesis in plants. Freezing temperatures lead to dehydration, increased membrane damage, loss of ions, increased disruption of protein, lipids and DNA, and finally necrosis and cell death (Yadav 2010; Sanghera et al. 2011; Lukatkin et al. 2012). The strategies employed by plants to tackle low‐temperature stress are tolerance and avoidance. Acclimation of plants to chilling and freezing temperatures over time results in diversion of the metabolic flux toward the synthesis of osmoprotectants such as soluble sugars, proline, and glycine betaine. Moreover, plants can tolerate cold stress by expressing proteins such as dehydrins, cold‐regulated proteins, antioxidative enzymes and HSPs that maintain homeostatic conditions in the cells. Above all, there are transcription factors governing the regulation of cold stress response. The C‐Repeat Binding Factor (CBF)/DREB responsive pathway offers one of the most important routes for the production of cold‐responsive proteins. Expression of CBF is controlled by ICE1 (inducer of CBF expression), a positive regulator of CBF3, and HOS1 (high expression of osmotically sensitive), a negative regulator of ICE1 (Chinnusamy et al. 2003; Janská et al. 2010; Rihan et al. 2017). Thus, overexpression of transcription factors positively regulating cold stress in transgenic crops can provide cold tolerance. Transgenic Arabidopsis and rice plants harboring AaDREB1 from Adonis amurensis, a cold‐tolerant plant, showed enhanced tolerance to low temperatures down to 4 °C for 12 days (Zong et al. 2016). PpCBF3 gene isolated from a cold‐tolerant perennial grass species, Kentucky bluegrass (Poa pratensis L.), when expressed in transgenic Arabidopsis plants, exhibited significant improvements in freezing tolerance (−20 °C). These plants had a lower percentage of chlorotic leaves, cellular electrolyte leakage and H2O2 and O2− content, and higher chlorophyll content and photochemical efficiency compared with the wild‐type control plants (Zhuang et al. 2015). Overexpression of OsCOIN, basic leucine zipper (bZIP) transcription factor, or a C2H2‐type zinc finger protein, OsZFP245 imparted tolerance to cold and drought with increased proline content in transgenic rice plants (Liu et al. 2007; Huang et al. 2009). Accumulation of proline is directly correlated with cold tolerance in most studies. Regulation of the cell cycle is another parameter in achieving cold tolerance. Overexpression of a MYB3R transcription factor, OsMYB3R‐2, in transgenic rice plants imparted cold tolerance at 4 °C for at least one week. These transgenic rice plants showed higher transcript levels of several G2/M phase‐specific genes, including OsCycB1;1, OsCycB2;1, OsCycB2;2, and OsCDC20.1, than in wild‐type plants in response to cold treatment (Ma et al. 2009). MYB3R transcription factors are known to regulate DREB and other transcription factors involved in cold tolerance such as COR15a and RCI2A (Dai et al. 2007). Moreover, there are some MYB genes which when downregulated impart cold tolerance. AtMYB14 gene is one of a kind wherein knocking it down in transgenic lines demonstrates freezing tolerance by regulating CBF genes under cold treatment (Chen et al. 2013a,b).
Hormonal signaling is yet another method of withstanding cold stress in plants. ABA‐, auxin‐, and ethylene‐regulated genes are known to be differentially expressed under cold stress. In the initial stages of cold stress, plants are protected from osmotic damage by the family of genes common to drought and salinity wherein ABA plays a critical role. Overexpression of the grapevine VaERF057, an ethylene‐signaling gene, enhanced cold tolerance of transgenic Arabidopsis by reducing membrane damage and increasing the activity of antioxidative enzymes such as superoxide dismutase, peroxidase, and catalase (Sun et al. 2016). OsCYP19‐4 gene, a member of the CYP5 family of auxin response factor guanine nucleotide exchange factors, improved cold tolerance in transgenic rice. These plants also displayed increased tiller and spike numbers and enhanced grain weight compared with the wild‐type plants (Yoon et al. 2015). There have been continuous successful efforts to generate cold‐tolerant lines by expressing genes such as osmotin, superoxide dismutase and peroxidases without any growth anomaly (Patade et al. 2013; Shafi et al. 2014).
Most of the studies on cold tolerance have been restricted to model crops such as rice and tomato. More information is required to understand the overriding response toward chilling and freezing stress and crosstalk of the regulatory genes between cold and drought/salt stress. In nonmodel crop plants, expressing MusaPIP1;2 in transgenic banana imparted cold tolerance (Sreedharan et al. 2013) and expressing DREB1A, DREB1B and SCOF‐1 in transgenic potatoes provided freezing tolerance under glasshouse conditions (Behnam et al. 2007; Movahedi et al. 2012; Kim et al. 2016). Expressing Arabidopsis CBF3 in transgenic eucalyptus provided cold tolerance under field conditions (Zhang et al. 2012). Two freezing‐tolerant Eucalyptus lines designated 427 and 435 cleared field trials except for some environmental concerns and are expected to receive approval for release in the near future.
1.4 Salinity Tolerance
Soil salinity is the biggest problem faced by farmers. It is increasing at an alarming rate and reducing cultivation dramatically. Soil salinity is increasing owing to decreasing rainfall, high rate of evaporation, irrigation with saline water and unsuitable cultural practices. Twenty percent of the total cultivated land and 33% of irrigated land is affected by high soil salinity (Shrivastava and Kumar 2015). Salinity stress lead to osmotic imbalance which eventually culminates in inactivation of enzymes, nutrient starvation, oxidative stress and cell death. High salt content in soil reduces water uptake through roots. Further, there is an increased uptake of Na+ and Cl− ions from the soil that reduces photosynthetic efficiency, negatively affecting growth and development (Turan et al. 2012; Deinlein et al. 2014). Plants can tolerate salt stress by overcoming the consequences of salinity by means such as excluding salts or sequestering and accumulating them in vacuoles, reducing osmotic stress by producing osmolytes like glycine betaine, trehalose, or proline, and producing antioxidants or enzymes to tackle ROS (Munns and Tester 2008; Turan et al. 2012; Roy et al. 2014). There are several genes and family of genes that can be used to improve salinity tolerance in crop plants through breeding or genetic engineering. Conventional plant breeding is being used to generate salt‐tolerant lines, but its scope remains limited owing to poor genetic variation. However, genetic engineering has been valuable in transferring genes from salt‐tolerant plants (halophytes and nonhalophytes) to major crops to achieve salt tolerance (Table 1.2).
Table 1.2 List of genes used to generate salt‐tolerant transgenic plants.
Target gene
Source of gene
Target plant
Evaluation
Functional change
References
OsNHX1
Oryza sativa
Zea mays
Greenhouse, field
More biomass, high grain yield
Chen et al.
2007a,b
GmDREB1
Glycine max
cv. Jinong 27
Triticum aestivum
L.
Field
Longer coleoptiles and radicles at the germination stage, greater root length and tiller number per plant at the seedling stage; upregulation of osmotic‐ and oxidative‐stress‐related proteins; higher levels of proline and betaine and lower levels of malondialdehyde and relative electrolyte leakage
Jiang et al.
2014
AhDREB1
Atriplex hortensis
Populus
(
Populus tomentosa
×
Populus bolleana
× P.
tomentosa
)
Field
Improved proline and chlorophyll contents, higher activities of peroxidase and superoxide dismutase
Lu et al.
2014
EcNAC1
Eleusine coracana
(L.)
Gaertn
Nicotiana tabacum
Greenhouse
Increased tolerance to oxidative stress, reduced ROS damage
Ramegowda et al.
2012
TaMYB2A
Arabidopsis
Greenhouse
Decreased rate of water loss, enhanced cell membrane stability, improved photosynthetic potential, and reduced osmotic potential
Mao et al.
2011
DnWRKY11
Dendrobium nobile
Nicotiana tabacum
cv.
Huangmiaoyu
Greenhouse
Higher germination rate, longer root length, higher activities of catalase, peroxidase, superoxide dismutase, and lower content of malonidialdehyde
Xu et al.
2014
GmFDL19
Glycine max
Glycine max
Greenhouse
Reduced accumulation of Na
+
ion content and upregulation of ABA/stress‐responsive genes
Li et al.
2017a,b,c
bMIPS1
Ipomoea batatas
Ipomoea batatas
Greenhouse, field
Enhanced photosynthesis, increased inositol content, reduced H
2
O
2
levels and increased expression of salt‐responsive genes
Zhai et al.
2016
AtVHXl
Arabidopsis thaliana
Arabidopsis thaliana
Greenhouse
Increased salt tolerance, increased vacuolar Na
+
/H
+
antiport activity
Apse et al.
1999
PvNHX1
Panicum virgatum
L.
Panicum virgatum
L.
Greenhouse
Higher shoot height, larger stem diameter, longer leaf length and width, increased proline accumulation, reduced malondialdehyde production, preserved cell membrane integrity
